The invention relates to a centrifugal pump of multistage type of construction, in which each pump stage has a casing consisting of one or more parts and an impeller arranged in said casing, the pump stages are arranged, for connection to flow-carrying systems, between inlet and outlet end pieces and are held between these by connectors, all the impellers are arranged on one pump shaft supported in at least two pump bearings, a pump shaft end is provided with a receptacle for a connector of a drive, and outer bearing means are arranged in the region of the end pieces in order to fasten the centrifugal pump at an installation location.
Centrifugal pumps of this type which are formed as linked pumps are designed for conveying a fluid at a high pressure level. They are formed as independent appliances, the pump shaft of which is connected to a drive machine, for example an electric motor or a turbine, with a coupling element being interposed. The centrifugal pump and the drive machine are mounted together on a baseplate or on a foundation. They are often used as multistage feedpumps in power plants or in other arrangements where a high pressure is required. As a result of the multistage construction and the arrangement of the pump stages between the end pieces, it is possible, during their production, to adapt in a simple way to different operating conditions by varying the number and type of construction of the pump stages. For this purpose, the connectors and the pump shaft are to be co-ordinated with the corresponding overall length of the centrifugal pump, and a baseplate or a pump foundation is to be designed to correspond to the overall length.
Centrifugal pumps having this general type of construction are known from DE 22 04 995 A1 and DE 26 14 163 B1 and from the KSB Centrifugal Pump Lexicon, third updated edition, page 185. Where these multistage linked pumps are concerned, the respective pump bearings of the pump shafts are arranged outside and at a distance from the end pieces of the centrifugal pump. The distance between the pump bearings is increased due to the necessary space for the shaft seals which are to be attached and by which fluid is prevented from emerging from the casing of the centrifugal pump. A large bearing distance between the shaft bearings which is due to this is a disadvantage in oscillatory terms, since unfavorable oscillations of the rotating component may occur as a result. Also, the absorption of pipeline forces which are conducted into the centrifugal pump via the end pieces has an adverse influence on the conditions of force of the centrifugal pump.
Outer support members serve to fasten such centrifugal pumps at the respective location of use and are provided on the end pieces or else between the end pieces of the centrifugal pump. An unfavorably selected position of these outer support members, which are generally configured as feet, battens or struts, may have, in respect of a built-in centrifugal pump, adverse effects on the oscillatory behavior of the rotating components.